During semiconductor wafer fabrication, patterned radiation can be used to produce very small lithographic patterns, such as nanometer-scale lithographic patterns, on a semiconductor wafer. In extreme ultraviolet (EUV) lithography, for example, a pattern formed on an EUV lithographic mask can be transferred to a semiconductor wafer by exposing a layer of resist formed on the semiconductor wafer to EUV light reflected from portions of a reflective surface.
Due to the very short wavelengths (high frequencies) used in EUV and other high resolution lithographic techniques, the patterning radiation utilized is highly absorbed by many resist materials. In addition, the radiation sources relied upon in some techniques are of limited brightness, further limiting the radiation dose available for lithographic patterning.
A conventional approach to compensating for low source brightness and the high absorbance of patterning radiation is to utilize a resist material including a photoactivated catalytic species, for example a photogenerated acid (PGA), to chemically amplify a latent image formed on the resist. However, heretofore unresolved difficulties in adequately controlling diffusion of PGAs at very small dimensions has limited the ability of chemically amplified resists to capture the ever finer patterns being produced in EUV and other high resolution lithographic techniques.